I would defiantly be against using the numbers to represent the workspaces because PieThrower would be the only area of the Shell where the workspaces would have numbers, which is confusing/not helpful. Also, I'm not keen on the icons of the apps for each workspace, it just complicates things.
I think the original mock-up using simple, clean arrows is the best way to go about it. For the extended view (more than one workspace) a double arrow (like fast forward buttons) would throw the window over two workspaces (my original suggestion). I like the arrows because its simple and to the point; one arrow will throw the window one workspace, two arrows will throw the window two workspaces, and so on. This works because most people have a feeling or visualization of where the current workspace (and their work) is in relation to the others, not by what number they are on, but simply by its position in the entire array (the visualization part is helped by the Overview, which displays the workspaces in position with respect to the others, not by their number or even what apps are running in them).
